From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Rybchenko Subject: Re: [PATCH] ethdev: add new offload flag to keep CRC Date: Wed, 20 Jun 2018 20:39:40 +0300 Message-ID: <5e17f673-e9e1-4b13-5b8d-9eccc575944f@solarflare.com> References: <20180608225709.19473-1-ferruh.yigit@intel.com> <20180619180230.72585-1-ferruh.yigit@intel.com> <9390200c-b113-5f22-99d4-21c42b5f56f3@solarflare.com> <271de83c-fc43-8136-a565-106c400ebb11@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Cc: To: Ferruh Yigit , Neil Horman , John McNamara , "Marko Kovacevic" , "John W. Linville" , Allain Legacy , "Matt Peters" , Ravi Kumar , "Ajit Khaparde" , Somnath Kotur , Rahul Lakkireddy , Wenzhuo Lu , Qi Zhang , Xiao Wang , Beilei Xing , Konstantin Ananyev , Adrien Mazarguil , Nelio Laranjeiro , Yongseok Koh , "Tomasz Duszynski" , Dmitri Epshtein , "Natalie Samsonov" Return-path: Received: from dispatch1-us1.ppe-hosted.com (dispatch1-us1.ppe-hosted.com [67.231.154.164]) by dpdk.org (Postfix) with ESMTP id 39D3A1B4EB for ; Wed, 20 Jun 2018 19:40:07 +0200 (CEST) In-Reply-To: <271de83c-fc43-8136-a565-106c400ebb11@intel.com> Content-Language: en-GB List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 06/20/2018 08:24 PM, Ferruh Yigit wrote: > On 6/20/2018 8:42 AM, Andrew Rybchenko wrote: >> On 06/19/2018 09:02 PM, Ferruh Yigit wrote: >>> DEV_RX_OFFLOAD_KEEP_CRC offload flag added. PMDs that supports keeping >>> CRC should advertise this offload capability. >>> >>> DEV_RX_OFFLOAD_CRC_STRIP flag will remain one more release >>> default behavior in PMDs are to keep the CRC until this flag removed >>> >>> Until DEV_RX_OFFLOAD_CRC_STRIP flag is removed: >>> - Setting both KEEP_CRC & CRC_STRIP is INVALID >>> - Setting only CRC_STRIP PMD should strip the CRC >>> - Setting only KEEP_CRC PMD should keep the CRC >>> - Not setting both PMD should keep the CRC >>> >>> A helper function rte_eth_dev_is_keep_crc() has been added to be able to >>> change the no flag behavior with minimal changes in PMDs. >>> >>> The PMDs that doesn't report the DEV_RX_OFFLOAD_KEEP_CRC offload can >>> remove rte_eth_dev_is_keep_crc() checks next release, related code >>> commented to help the maintenance task. >>> >>> And DEV_RX_OFFLOAD_CRC_STRIP has been added to virtual drivers since >>> they don't use CRC at all, when an application requires this offload >>> virtual PMDs should not return error. >>> >>> Signed-off-by: Ferruh Yigit >>> --- >> <...> >> >>> diff --git a/lib/librte_ethdev/rte_ethdev_driver.h b/lib/librte_ethdev/rte_ethdev_driver.h >>> index c9c825e3f..09a42f8c2 100644 >>> --- a/lib/librte_ethdev/rte_ethdev_driver.h >>> +++ b/lib/librte_ethdev/rte_ethdev_driver.h >>> @@ -325,6 +325,26 @@ typedef int (*ethdev_uninit_t)(struct rte_eth_dev *ethdev); >>> int __rte_experimental >>> rte_eth_dev_destroy(struct rte_eth_dev *ethdev, ethdev_uninit_t ethdev_uninit); >>> >>> +/** >>> + * PMD helper function to check if keeping CRC is requested >>> + * >>> + * @param rx_offloads >>> + * offloads variable >>> + * >>> + * @return >>> + * Return positive if keeping CRC is requested, >>> + * zero if stripping CRC is requested >>> + */ >>> +static inline int >>> +rte_eth_dev_is_keep_crc(uint64_t rx_offloads) >>> +{ >>> + if (rx_offloads & DEV_RX_OFFLOAD_CRC_STRIP) >>> + return 0; >>> + >>> + /* no KEEP_CRC or CRC_STRIP offload flags means keep CRC */ >>> + return 1; >>> +} >>> + >>> #ifdef __cplusplus >>> } >>> #endif >> A couple of control questions about the function: >>  - shouldn't __rte_experimental be used? > This is an internal function, not API, so I think doesn't require to be > experimental. Just to make my thoughts clear: description does not say that it is an internal. So, nothing prevents external entities to use it. Changes will be API breakage. >>  - if the function remains in the future, it will be a bit asymmetric vs other >>    offload flags. Right now it is clear why the function is introduced, but >>    it is the question if the function should remain or go away in the future >>    (as far as I know no other offload flag has similar function to check). > No other offloads don't have similar functions, this is kind special. > > There will be more changes related CRC next release, CRC_STRIP will be removed > and no flag will mean strip CRC. So the conditions to is_keep_crc will be changed. > This function is to manage this change easier, localize the information in to > single function to make it easy to update later. It is perfectly clear why it is required right now and introduced (as I said from the very beginning). Yes, it is will be the history which explains why it is so, but if we make a step forward and discard the history it will look asymmetric - it will be a function which checks single bit. It is really minor and 100% up to you. Many thanks for reply.